嗜热菌在废水处理中的应用及研究进展

介绍了嗜热菌的分类、耐热机制及其在废水处理中的应用.通过实例阐明了利用嗜热菌处理废水的可行性.同时介绍了高温好氧工艺、高温厌氧工艺及其组合工艺的优缺点,并展望了今后的研究方向.     

AOA-SBR工艺用于城市污水同步脱氮除磷

以城市污水为研究对象，考察了不同COD／N／P对厌氧／好氧／兼氧（AOA）．SBR工艺脱氮除磷效果的影响。经过3个月稳定运行，当COD：N：P-800：24：11时，AOA．SBR工艺对污水中有机物、氨氮和磷的去除率分别为100％、84％和93％。实验通过提高有机物浓度削弱聚磷菌（PAOs）与聚糖菌（GAOs）竞争底物的能力，抑制了PAOs好氧放磷速率。当COD=800mg／L时，GAOs和PAOs厌氧乙酸摄取量之比为l：9。此外，实验采用兼氧／好氧吸磷速率比，对反硝化聚磷菌数量（DNPAOs）进行估算，结果表明AOA-SBR工艺比值明显高于A20和AO工艺。因此，通过调节进水有机物浓度，可使DNPAOs在AOA-SBR同步脱氮除磷过程中发挥重要作用。     

染料废水的处理工艺

作者自行设计一个上流式厌氧污泥床（UASB）用于染料废水处理工艺条件的优化选择，由此，提出一个针对染料废水的处理工艺方案，并将其应用于某染料厂综合废水的处理，COD的总去除率达到89．8％。结果表明，本工艺比该厂现行工艺的处理效果明显优越，各污染物去除率均有不同程度的提高。     

偏二甲肼污水的好氧生物降解研究

偏二甲肼(UDMH)是液体推进剂的主体燃料,其对水体的污染一直倍受重视。生物降解技术是近年来发展迅猛的一种新型污水处理方法。笔者利用其中一种生物降解技术——好氧活性污泥处理UDMH污水,经过驯化培菌60d所得到的活性污泥对污水中UDMH去除率达到98%,pH值、污泥浓度、温度、搅拌速度、UDMH浓度都能影响活性污泥的降解效果。活性污泥降解UDMH最佳条件为pH值7.0-7.5,污泥质量浓度1.60-1.28g/L、温度25-30℃、搅拌速度80-100r/min,UDMH质量浓度≤1580mg/L。     

单级预热式自动升温高温好氧消化工艺处理剩余活性污泥

用自行设计的单级预热式自动升温高温好氧消化工艺系统处理浓缩池中的剩余活性污泥,采用间歇式操作方式,研究了进泥浓度、搅拌速率、曝气量、固体停留时间对污泥稳定化效果的影响,并对污泥稳定化和无害化效果进行了评价,同时对消化后污泥的脱水性能和pH值进行了测试分析。结果表明,当进泥含固率为4.3%～6.4%、进泥挥发性有机物(VSS)质量浓度为33.4～44.1 g/L、搅拌速率为100～110 r/min、曝气量为0.10～0.12 m3/h、固体停留时间为10天时,污泥稳定化效果最好,反应器内温度可维持在54.5～56.8℃,对VSS的去除率平均达到53.2%,脱氢酶活性(DHA)下降74%,此时,病原菌的灭活率达到100%,出泥达到了美国环保局规定的A级生物固体(污泥)的标准;在此工艺条件下发现消化后的污泥脱水性能变差,而pH值升高,这是由于在消化过程中产生的溶胞现象所致。     

好氧颗粒污泥处理城市生活污水

在SBAR反应器中培养出成熟好氧颗粒污泥，并应用于处理实际城市生活污水。在逐步增加城市生活污水COD含量的情况下，考察了颗粒污泥对COD以及NH3-N的处理效果，平均去除率分别达70％和90％。实验过程中反应器中不同阶段颗粒污泥的生物量浓度基本在2000—3500mg／L范围内变化，且一直具有良好的沉降陛，污泥容积指数（SVI）为35～50mL／gMLSS．本文还初步探讨了在利用好氧颗粒污泥处理实际城市生活污水过程中的同步硝化和反硝化作用。     

Potassium tert‐Butoxide‐Mediated Amine Acyl Exchange Reaction of N,N‐Disubstituted Formamides with Aromatic Carbonyl Derivatives via Sequential C?N Bond Cleavage/Formation: an Approach to Aromatic Amides

A novel potassium tert‐butoxide‐mediated amine acyl exchange of N,N‐disubstituted formamides with aromatic carbonyl derivatives in a sequential C N bond cleavage/formation process leading to aromatic amides is described. This methodology tolerates a wide range of aromatic carbonyl compounds, including aromatic aldehydes, acyl chlorides, unactivated esters, and acid anhydrides. The usage of inexpensive and readily available reagents, broad substrate scope, and the simple, mild (50 °C) and transition metal‐free conditions make this protocol very practical. In addition, a plausible reaction mechanism is proposed on the basis of experimental observations.

     

Integrated Process of Aerobic Oxidation–Olefination–Asymmetric C?C Bond Formation Catalyzed by Robust Heterogeneous Gold/Palladium and Chirally Modified Rhodium Nanoparticles

We have achieved an integrated process of oxidation–olefination–asymmetric 1,4‐addition reactions under aerobic and aqueous conditions using metal nanoparticles as robust heterogeneous catalysts. A tandem process of aerobic oxidation and Horner–Wadsworth–Emmons olefination was successfully catalyzed by gold/palladium bimetallic nanoparticles. A wide range of substrates gave the desired products in high yields and excellent selectivities. This tandem process was further connected with an asymmetric 1,4‐addition reaction catalyzed by chiral rhodium nanoparticles to achieve a challenging three‐step, one‐pot sequential reaction. Various types of esters with a chiral center at the β‐position were obtained from readily available and stable alcohols and arylboronic acids in high yields with high enantioselectivities in a one‐pot sequential reaction integrating three transformations.

     

Evaluation and Development of a Thermophilic Aerobic Digester at Castle Donington Sewage-Treatment Works

An investigation into the practicality of thermophilic aerobic digestion has been in progress at Castle Donington since 1989. The work has been carried out in a glassed steel insulated digester of 123 m³ capacity. Both auto-entraining and blower-assisted venturi systems have been evaluated.
Both aeration systems were able, under favourable conditions, to remove at least 50% of the sludge COD. It was found that the additional flexibility of the blower venturi combination was necessary to accommodate crude sludges varying from 2% to 12% dry solids.
Originally the plant was intended to operate at above 55C with a 10-day retention period. In practice retention periods at this temperature have been at least 15 days. The process has proved relatively susceptible to inhibition and requires the air supply to be closely matched to the load.
The revenue costs have been, at best, around 47.3/tDS. This is competitive with small-scale anaerobic digestion, but not with the large digestion centre approach widely used in the UK. Unless pasteurization becomes a requirement for agricultural disposal, thermophilic aerobic digestion is unlikely to find wide use in this country.     

The effect of hydraulic retention time on granular sludge biomass in treating textile wastewater

The physical characteristics, microbial activities and kinetic properties of the granular sludge biomass were investigated under the influence of different hydraulic retention times (HRT) along with the performance of the system in removal of color and COD of synthetic textile wastewater. The study was conducted in a column reactor operated according to a sequential batch reactor with a sequence of anaerobic and aerobic reaction phases. Six stages of different HRTs and different anaerobic and aerobic reaction time were evaluated. It was observed that the increase in HRT resulted in the reduction of organic loading rate (OLR). This has caused a decrease in biomass concentration (MLSS), reduction in mean size of the granules, lowered the settling ability of the granules and reduction of oxygen uptake rate (OUR), overall specific biomass growth rate (ì_overall), endogeneous decay rate (k_d) and biomass yield (Y_obs, Y). When the OLR was increased by adding carbon sources (glucose, sodium acetate and ethanol), there was a slight increase in the MLSS, the granules mean size, ì_overall, and biomass yield. Under high HRT, increasing the anaerobic to aerobic reaction time ratio caused an increase in the concentration of MLSS, mean size of granules and lowered the SVI value and biomass yield. The ì_overall and biomass yield increased with the reduction in anaerobic/aerobic time ratio. The HRT of 24 h with anaerobic and aerobic reaction time of 17.8 and 5.8 h respectively appear to be the best cycle operation of SBR. Under these conditions, not only the physical properties of the biogranules have improved, the highest removal of color (i.e. 94.1 ± 0.6%) and organics (i.e. 86.5 ± 0.5%) of the synthetic textile dyeing wastewater have been achieved.